Nonwoven fabrics, or nonwovens, have gained great acceptance in the industry for a wide range of applications, particularly as replacements for woven fabrics in constructions such as for facings or topsheets in diapers, incontinent pads, bed pads, sanitary napkins, hospital gowns, disposable wipes, and other single and multi-use nonwovens. For such uses it is desirable to produce a nonwoven which closely resembles the drape, flexibility and softness (hand) of a textile and yet is as strong as possible even when wet.
When an adhesive binder is used to bond the loosely assembled webs of fibers in the nonwoven, the particular binder employed plays an important role in determining the final properties of the nonwoven since it contributes to the presence or absence of a wide range of properties including the wet and dry tensile, tear strength, softness, absorbency, and resilience as well as the visual aesthetics. Acrylic latices have generally been used as binders where softness is the most important criteria, however the resultant nonwovens have suffered in strength. Ethylene/vinyl acetate-based binders yield the necessary strength properties but are deficient in softness for some applications requiring extreme softness. Efforts have been made to soften the ethylene/vinyl acetate binders by interpolymerization with the appropriate acrylate functionalities; however, this has also only been acomplished with a consequent reduction in the strength of the binder. As a result of this loss in strength, no more than 25% by weight acrylate functional had been employed in ethylene/vinyl acetate based binders for non-wovens.
Copending application Ser. No. 749,208 filed June 27, 1985, now U.S. Pat. No. 4,610,920, teaches the preparation of ethylene/vinyl acetate/acrylate/N-methylol copolymers containing higher levels of acrylates and the use thereof as nonwoven binders.